This invention relates to an attachment structure for an aligning type roller clutch which can be utilized in rotation drive system of a washing and dehydrating tank for a full automatic washing machine.
In a full automatic washing machine, since the wash and dehydration of the washing are effected in a common tank (washing and dehydrating tank), the washing and dehydrating tank is at rest during washing and is rotated only during dehydration. The rotation control of this washing and dehydrating tank is effected by controlling the rotation of a cylindrical tank shaft extending downwardly from the middle portion of its bottom. That is, inserted in the cylindrical tank shaft is a fan shaft rotatable in both directions connected to a rotation drive source. During washing, only the fan shaft is rotated while restraining the rotation of the cylindrical tank shaft by means of a one-way clutch and brake belt, and during dehydration, the restraint from the brake belt is removed to allow the fan shaft to rotate in the free direction of the one-way clutch so as to rotate the cylindrical tank shaft and fan shaft together. And on completion of dehydration, the brake belt is actuated to stop rotation of the cylindrical tank shaft.
As for such one-way clutch, a roller clutch is in frequent use. A roller clutch comprises, for example, an outer ring having a plurality of cam surfaces on its inner peripheral surface and defining a plurality of wedge spaces between the individual cam surfaces and the outer peripheral surface of a rotatable a shaft to be controlled, needle rollers disposed in the wedge spaces, a retainer having a plurality of pockets for receiving the needle rollers, and spring means for urging the needle rollers toward the narrow clearance sides of the wedge spaces. When the rotatable shaft is rotated in the one direction, the needle rollers engage the narrow clearances of the wedge spaces to transmit torque. Reversely, when the rotatable shaft is rotated in the other direction, the friction forces between the needle rollers and the rotatable shaft move the needle rollers against the force of the spring means until they leave the narrow clearances of the wedge spaces, whereby transmission of torque is cut off. The spring means causes the needle rollers to move quickly from the released state to the engaged state, to improve the response characteristics of the clutch.
The original function of the roller clutch resides in the transmission and cut-off of torque and since the roller clutch itself has no sufficient load supporting ability, it has been common practice to use both a roller clutch and a rolling contact bearing in order for the rolling contact bearing to perform the function of supporting the rotatable shaft and for the roller clutch to perform the original function of torque transmission and cut-off. In concrete, two types are known: the so-called separate type in which a roller clutch and a rolling contact bearing are separately attached to the main frame, and the unit type in which a unitized assembly of a roller clutch and a rolling contact bearing is attached to the main frame. As for the separate type, it has been common practice to fix a clutch housing to the main frame by bolts and nuts.
Depending on the attachment error or the like, inclination develops in the rotatable shaft, and if the angle of inclination is too large, an unbalanced load acts on the outer ring of the roller clutch, so that the torque is not uniformly transmitted to the cam surfaces, incurring the danger of the durability of the cam surfaces being adversely influenced. Also there is an anxiety about the durability of the spring means which presses the needle rollers. Among other things, in a full automatic washing machine, since a high centrifugal force is applied to the rotatable shaft, it is necessary to take measures against eccentricity and inclination of the rotatable shaft.
In the separate type, however, the clutch housing has to be fixed to the main frame, and when bolts and nuts are used for fixing, the problem is that the fixing operation takes considerable man-hour.